Optical waveguides consist of a transparent waveguiding core surrounded by transparent materials of lower indices of refraction Several general methods are utilized for the fabrication of optical waveguides
Optical waveguides fabricated in GaAs/AlGaAs structures by laser-assisted etching has been reported in Integrated And Guided-Wave Optics, 1989 Technical Digest Series, 4, 64-67 (Optical Society of America).
U.S. Pat. No. 4,842,677 describes excimer laser etching of high resolution conductive patterns involving the use of an organic polymeric resist Other publications relating to photoablation of organic polymers include J. Appl. Phys., 66(3), (1989).
Methods of fabricating organic waveguides are a newly evolving technology. There are inherent disadvantages in the practice of the various known methods, such as difficult multi-step procedures which do not provide reliable quality control and reproducibility Typical organic waveguiding media exhibit high optical scattering losses.
A review article in Journal Of Lightwave Technology, 7(10), 1445 (1989) describes several polymeric channel waveguide fabrication routes, such as etching methods which include wet chemistry etching, reactive ion etching, excimer laser ablation, and the like.
New developments in electrooptically active organic waveguide technology involve the use of polymers with molecular groups that exhibit second order nonlinear optical susceptibility in side chains or in the main chain. Side chain polymers are described in U.S. Pat. Nos. 4,801,670; 4,804,255; 4,808,332; 4,882,865; and 4,865,406.
When a polymer waveguiding thin film medium is subjected to an electric field to induce a noncentrosymmetric molecular orientation of the nonlinear optically active groups, the waveguiding medium exhibits second order nonlinear optical susceptibility .chi..sup.(2) and linear electrooptic effects.
The electrooptic activity of the polymer waveguiding medium is proportional to the degree of noncentrosymmetric molecular orientation induced by electric field poling, which in turn is proportional to the strength of the applied electric field. The amount of voltage which can be applied for electric field poling is limited because dielectric breakdown occurs, due to extrinsic factors such as field enhancement at the electrode edges. Consequently a typical noncentrosymmetric organic waveguide medium has a linear electrooptic constant r of less than about 20 pm/V at 1.3 .mu.m.
There is continuing interest in the development of new and improved techniques for the fabrication of organic optical waveguides which overcome some of the inherent deficiencies of optical waveguide formation in transparent organic media.
Accordingly, it is an object of this invention to provide an improved method for the production of organic optical waveguides.
It is another object of this invention to provide a method for the production of noncentrosymmetric polymeric optical waveguides by electric field poling with electrodes having a novel structural configuration.
It is a further object of this invention to provide polymeric optical waveguides which have a two-dimensional channel waveguiding structure, and which have a linear electrooptic constant r of at least about 20 pm/V.
Other objects and advantages of the present invention shall become apparent from the accompanying description and Examples.